The most popular rifle cartridge in the United States is the 223 Remington, which for the military is known as the 5.56x45 cartridge (also known as the 5.56 NATO). These two, the 223 and 5.56 share the same outside dimensions, as well as the bullet. Most people think the 22 caliber 223 Remington (and 5.56) use a .223 diameter bullet, but that is not the case, they actually use a .224 diameter bullet. The big difference between these two is the 5.56 rifle has a slightly longer throat (.125"), which allows for an additional grain of powder. If a 5.56 NATO loaded round is placed in a standard 223 rifle, the shorter throat causes the pressure to build to over 65,000 PSI, which is much higher than the rated 223 pressure of 55,000 PSI. The case of the 5.56 may be slightly thicker to allow for the higher pressure. 5.56 military brass has a crimped primer, however the 5.56 civilian brass does not.
Common bullet weights for the .223 bullets are from 40 grain to 90 grain, with the 55 grains being the most common. Obviously, the lighter the bullet, the faster it travels, which makes it ideal for varmint hunting. The heavier the bullet, the greater the need for more accuracy, so a faster twist is needed. Normally a 1:12 twist for a 55 grain bullet is sufficient, however 1:7 is much for a heaver bullet, such as a 70 grain+.
For plinking, the king is the 55 grain Full Metal Jacket (FMJ) bullets, these are the most common bullets on the market, made from everyone from Berry’s, Hornady, Speer, etc. But for hunting and other uses the VMAX bullets from Hornady are a good choice. With Match Kings from Sierra being a great investment too.
Below are our 223 reloading supplies we currently supply, with those in stock shown at the top of the listing. Some such as Berrys and Hornady are bulk 223 bullets for reloading.